Monkeys as art-critics, 1889. Here's an oddity for you, a fin de siècle artist before his time; he seems to have lived in Munich with a houseful of monkeys (hence their frequent appearance in his work). More about him here:
Atropa Belladonna, otherwise known as Deadly Nightshade!
The Anatomist, 1869
Another monkey to end with, this time a philosophical one.
Illustrations to Faust: